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4.4 Other tree management practices

Hedges and windrows

The planting of hedges and windrows in Murang'a District and in many other areas remains common. The preferred species in high rainfall areas include an exotic species of cypress (Cupressus lusitanica), as well as mubage (Caesalpinia decapetala), mukawa (Carissa edulis), kaiaba (Dovyalis caffra), and mutundu (Croton macrostachyus). In lower rainfall parts of the district, the dominant species is kariaria (Euphorbia tirucalli). Hedges are often allowed to become windrows. The three dominant windrow species are cypress, mubariiti (Grevillea robusta), and mukinduri (Croton megalocarpus).

Cypress is very commonly managed as a "multi-story hedge." Every 3 metres or so along a tightly-clipped hedge, a stem will be left untrimmed, and will grow into a full-sized tree. In some parts of Kikuyu country, these stems are side-pruned. The branches are used for fuelwood, or are sometimes used to make furniture, or small farm structures such as cattle enclosures and fences. Side pruning also increases the light that is available to crops. The stems are occasionally felled by pitsawyers who convert them into sawn timber. Cypress is usually only planted in rows; individual stems are seldom planted, except occasionally for shade around households.

Cupressus lusitanica was first introduced in Kenya sometime before 1920, although the exact date is uncertain. The planting of cypress on farms in Murang'a and other Kikuyu areas for saw logs was first noted by the Forest Department in the mid-1940s when the practice was reportedly quite widespread. Plantings apparently conflicted with other land uses that were deemed to be more important, and the Department noted that the widespread planting of cypress "may not be such a desirable development as it appears unless such planting is confined mainly to the steeper hillsides." (FD 1944:7)

Cypress is especially easy to regenerate. On-farm nurseries are believed to account for the bulk of new plantings, although it is still one of the major species grown in Forest Department nurseries and sold to farmers. The Department sells at heavily subsidized prices, although seedlings are often resold at much higher prices.

The two other tree species that are most common on or near smallholders' lands are Mubariiti (Grevillea robusta) and Mukinduri (Croton megalocarpus). G.robusta is occasionally grown and managed in windrows much like cypress and is used for both fuelwood and timber and for small farm structures. Unlike cypress, how ever, it is often planted in and around fields as well as in woodlots. It was originally introduced as a shade tree for coffee plantations (and is discussed below in this context). C.megalocarpus is a fast-growing species with a high, twisted canopy. It is unsuitable for building timber, but is occasionally harvested for woodfuel. It doesn't compete too heavily with crops. It is maintained primarily for its amenity value.

Fig. 4.4 Boundary planting of Cypress (Cupressus lusitanica) Murang'a District, 1990.

Photo: Dewees

Block plantings

Contiguous blocks of trees are sometimes planted over large areas. It has been estimated that there are around 6,000 hectares of woodlots in Murang'a District, and that aggregate woodlot areas in high potential zones of Kenya total around 80,000 ha (World Bank 1987:14). The effect of block plantings on the rural economy is poorly understood, but the impact must be considerable. The primary block planting species are black wattle (Acacia mearnsii), the dominant woodlot species in Murang'a District, and eucalyptus. There are also small block plantings of G.robusta in some areas, but these are more commonly planted in fields and in windrows.

Trees and livestock management

Livestock ownership, the main means of exchange amongst the Kikuyu, generally involved some form of tree cultivation and management. Cattle enclosures were a basic feature of the homestead. Enclosures were generally reinforced with cuttings from fast growing species such as F.natalensis. murigono (Clerodendrum johnstonii), and muhuti (Erythrina abyssinica) which eventually formed living fences. In the 1940s, an Assistant Agricultural Officer, L.A. Elmer noted the predominance of mutura (Solanum aculeastrum or S.marginatum) which was used in living fences for Kikuyu cattle enclosures. He recommended that European farmers adopt these species as alternatives to expensive wire fencing and described in great detail how to propagate and plant them out (Elmer 1944). The wood of mubiru muiru (Vangueria linearisepala) was also used in cattle enclosures, but it was seldom planted as a living hedge.

There were fairly sophisticated strategies of stall-feeding that increased productivity and limited disease. C.zimmermannii. sometimes planted to demarcate the boundaries of the homestead, was also planted in the main courtyard and was used to suspend fodder for goats and sheep, protecting it from contamination. Stall-fed animals rarely, if ever, suffered from intestinal worms. Usually, small huts would be used for keeping stall-fed animals, and the animals would rarely leave them until they were ready for slaughter. They were prized for their fat content, which would be used for cooking and for preparing skins (Lyne Watt 1942: 109).

The most common sources of livestock fodder were sweet potato vines. During times of famine, a number of species were used as alternatives. These were generally climbing bindweeds and creepers, called rather generically ihurura (Ipomea sp. and Glycine sp.). There were just a few tree species that were used for fodder. These included muheregendi (Grewia similis) which made very good goat food, and muhethu (Trema orientalis).

Tree replacement

A final tree planting practice which bears mention was tree replacement. Trees often had negative and positive features which might have been associated with an event that had taken place in the vicinity or which might have been a function of the species and its relationship to spirits and to magic. The ficus F.natalensis was a tree with particularly strong associations, both positive and negative. They were generally chosen by diviners as sacred trees for the sub-clan, though only specific trees served this function. Sub-clan ceremonies and sacrifices were held by these trees and persons accused of crimes could seek sanctuary at the foot of a sacred tree. F.natalensis trees only had positive associations if they were planted. Naturally-sprouted seedlings were uprooted and a tree with a positive association would be planted in its place.

These trees and woody shrubs were generally muthakwa (Vernonia auriculifera) easily recognizable because of its deep purple flowers, mukenia (Lantana trifolia) or mukeu (Dombeya sp.). They were commonly used as sacred trees for household ceremonies and sacrifices. V.auriculifera was the most common of these. It was widely-used in all manner of ceremonies and was associated with "good" magic. It was specifically planted as a replacement tree under three circumstances: to replace uprooted F.natalensis trees; to replace a tree that had been cut down to make a cattle trough; and to replace a tree that had been used by someone for hanging themselves. Lantana trifolia was planted for the same reasons as V.auriculifera. but in addition it would be planted in place of a sugar cane plant that had flowered and been uprooted, or in place of a banana tree that had been slashed in anger with a knife. Dombeya sp was less frequently planted than these other species, but was still recognized as a "good" tree (Leakey 1977:1313-1314;1343-1344 and 1347).

Shade and other trees

Brief mention should be made of a number of other trees of economic value. The two other most frequently found trees on farms in Central Province are Grevillea robusta and eucalyptus. Grevillea first became popular in Kenya as a coffee and tea shade tree. Young coffee and tea seedlings require protection from the sun, and also benefit from protection from wind (Warren 1941:16). Grevillea, as a fast growing tree which is relatively easy to regenerate, filled that role. It was adopted by coffee planters from the very earliest days of the industry in Kenya and by 1910 the Forest Department had started planting it in mixed stands with cypress. In the 1940s, it was widely recommended as a timber tree for planting at altitudes below 2,000 metres, while cypress was recommended for higher altitudes (Graham 1945:133).

Fig. 4.5 Grevillea robustainterplanted with smallholder coffee and heavily side pruned.

Photo: Dewees

The tree has a wide range of other uses. Leaf litter is widely used in locally-developed green manure agroforestry systems in Central Province. The wood is appreciated as a fuel because it dries quickly. Much like on-farm cypress tree management, the branches are usually heavily pruned for fuel and the construction of small farm buildings.

The practice of planting trees with tea and coffee came into question in the 1960s. Research carried out at the East African Agriculture and Forestry Research Organization (EAAFRO) suggested that reduced windspeeds in tea estates increased the temperature extremes, resulting in higher temperatures during the day and lower temperatures during the night (Ripley undated:80).

Grevillea has long been associated with a high incidence of the root-rot Armillariamellea in coffee and tea (Wallace 1935 and FD 1924:22). This fact, coupled with the findings of EAAFRO, has brought the tree into some disfavour amongst commercial coffee and tea growers, but it remains extremely popular amongst smallholders in many areas.

Eucalyptus was first widely promoted in Central Province in the 1930s, but it never became as popular there as it did in Western Kenya as a farm tree. It was introduced as a fast-growing pole and fuelwood tree. In other areas, it was widely planted to provide fuelwood for the railways. Generally, however, eucalyptus trees have a, far more limited range of values than trees like grevillea, wattle, or cypress even though growth is much faster. The most common species planted on farms are E.grandis and E.saligna, as well as related hybrids which have developed over the many years these trees have been cultivated. In drier areas, E.camaldulensis predominates.

Fig. 4.6 Smallholder-grown eucalyptus timber, split and stacked by the roadside for sale as fuelwood

Photo: Dewees

One of the eucalyptus tree's advantages was that it could be planted on swampy or water-logged soils, and would tend to dry them out and make them suitable for cultivation. Generally, E.robusta was preferred for this role. One of the Kikuyu names for eucalyptus, munyua maai, literally means "the drinker of water". The agricultural extension services have tried, without much success, to discourage the planting of the trees because of their alleged impacts on stream flows.

4.5 Summary: Trees as part of traditional land use practices

There are strong traditions of tree cultivation and management in Kikuyu areas of Kenya. Boundary demarcation with trees was a particularly common practice, both for marking off boundaries of the sub-clan land holding as well as for marking off divisions of the sub-clan land and divisions within the household. Trees were planted as living hedges around livestock enclosures, and were incorporated into village fortifications. Trees had both positive and negative magical and spiritual associations, and several species were widely planted because of their "good" characteristics. Timber production largely came from trees that were protected in sub-clan controlled forest reserves, from farm trees, or from trees that had been left standing on farmlands after the forest had been cleared.

It is unlikely that the guarantees of private tree ownership per se, actually encouraged farmers to plant more trees. In fact, the ownership of planted trees had long been guaranteed by customary law. Planted trees always belonged to whomever planted them, but only as long as they held some sort of cultivation rights. The Registered Land Act increased the security of these rights, and it was this security which likely had a greater impact on the farmer's interest in tree planting and in making other improvements to the land. Finally, changing patterns of land tenure and the wholesale governmental reservation of large stands of forests probably strengthened the tendency to use trees for boundary demarcation, but jeopardized traditional forest management and reservation practices.

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